only if you already have the source, the GPL also guarantees that you can get the source even if you don't have it.
Of course, vendors will often do this with GPLed code too, and lawsuits are relatively few and far between. (Many thanks to SFC/SFLC for putting scarce resources towards this when possible.)
Because of this, although I appreciate the open-endedness of the MIT/BSD licenses for end user software, I do prefer the GPL for anything that may become infrastructure.
GPL software requires preserving them transitively and requires derivative works using the licensed software as a component to provide them.
MPL requires preserving them transitively.
BSD/Apache/MIT don't require preserving them, but still require the resulting software to include the original license & attribution. In the case of a closed-source program distributing (say) MIT-licensed software with proprietary modifications, the resulting binary is still released partly under the MIT license & includes the MIT license text, but doesn't include the source code.